refactor(tazjin/rlox): Introduce declarations in parser
Change-Id: I873fdd53319ec36da18926d9477e809a69dbace7 Reviewed-on: https://cl.tvl.fyi/c/depot/+/2288 Reviewed-by: tazjin <mail@tazj.in> Tested-by: BuildkiteCI
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2 changed files with 37 additions and 16 deletions
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@ -1,5 +1,5 @@
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use crate::errors::{report, Error, ErrorKind};
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use crate::parser::{self, Expr, Literal, Program, Statement};
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use crate::parser::{self, Declaration, Expr, Literal, Program, Statement};
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use crate::scanner::{self, TokenKind};
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// Run some Lox code and print it to stdout
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@ -104,16 +104,24 @@ fn eval<'a>(expr: &Expr<'a>) -> Result<Literal, Error> {
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}
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}
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fn run_program<'a>(program: &Program<'a>) -> Result<(), Error> {
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for stmt in program {
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match stmt {
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Statement::Expr(expr) => {
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eval(expr)?;
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}
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Statement::Print(expr) => {
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let result = eval(expr)?;
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println!("{:?}", result)
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}
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fn run_stmt<'a>(stmt: &Statement<'a>) -> Result<(), Error> {
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match stmt {
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Statement::Expr(expr) => {
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eval(expr)?;
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}
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Statement::Print(expr) => {
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let result = eval(expr)?;
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println!("{:?}", result)
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}
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}
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Ok(())
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}
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fn run_program<'a>(program: &Program<'a>) -> Result<(), Error> {
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for decl in program {
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match decl {
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Declaration::Stmt(stmt) => run_stmt(stmt)?,
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}
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}
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@ -48,12 +48,20 @@ pub enum Statement<'a> {
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Print(Expr<'a>),
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}
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pub type Program<'a> = Vec<Statement<'a>>;
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#[derive(Debug)]
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pub enum Declaration<'a> {
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Stmt(Statement<'a>),
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}
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pub type Program<'a> = Vec<Declaration<'a>>;
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// Parser
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/*
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program → statement* EOF ;
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program → declaration* EOF ;
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declaration → varDecl
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| statement ;
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statement → exprStmt
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| printStmt ;
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@ -79,10 +87,15 @@ struct Parser<'a> {
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type ExprResult<'a> = Result<Expr<'a>, Error>;
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type StmtResult<'a> = Result<Statement<'a>, Error>;
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type DeclResult<'a> = Result<Declaration<'a>, Error>;
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impl<'a> Parser<'a> {
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// recursive-descent parser functions
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fn declaration(&mut self) -> DeclResult<'a> {
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Ok(Declaration::Stmt(self.statement()?))
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}
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fn statement(&mut self) -> StmtResult<'a> {
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if self.match_token(&[TokenKind::Print]) {
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self.print_statement()
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@ -274,13 +287,13 @@ pub fn parse<'a>(tokens: Vec<Token<'a>>) -> Result<Program<'a>, Vec<Error>> {
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let mut errors: Vec<Error> = vec![];
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while !parser.is_at_end() {
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match parser.statement() {
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match parser.declaration() {
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Err(err) => {
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errors.push(err);
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parser.synchronise();
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}
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Ok(stmt) => {
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program.push(stmt);
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Ok(decl) => {
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program.push(decl);
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}
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}
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}
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